I keep getting subject lines that I had edited showing up on the wrong message. So if I changed the subject line of a message to 'Joe's email address', I might look at another email in a different folder, and the subject line would say, "Joe's email address' instead of the real subject line. This is an important feature for me to have to filter lots of client emails. Anyone else have the problem? I"ve tried compressing the folders without success.

That's why I suggested to backup those files first, so if anything goes wrong you can always revert back by copying them back to their original location (while Barca is not running).

.IDB is an index file. I'm not quire sure instantly whether it stores any data that the .mbx file doesn't. If anything, it's something minor like whether message was tagged or not, or pointer to the follow-up message (replies to that message stored in Sent folder).

Right...that's what I was afraid of. I need those pointers so I know that I replied to a client and what I said. Otherwise, I'd have to do a search every time I need to find the thread. I can try deleting the .idb but I'm not sure it's going to work for me (and yes, I always back up!).

I have found this problem (change a subject causes a change to another message than intended) only happens when I change the subject of a message in the "Search" results folder or after I filtered messages with the "Quick Filter" - you know "Type text to focus on".

Since I noticed this, I only change subjects in the real folders (not the virtual ones) and never had this problem anymore.

I was wrong, just checked it and it seems that pointers to the messages sent as replies to the original message, are not lost, neither annotations nor message markings, only message tagging status is lost (if you use message tagging Ctrl+T), from what I could see, when .idb file is deleted.